The invention relates to a diaphragm pump with an annular working chamber and an annular diaphragm, which is fixed at its outer peripheral region and at its inner edge region. The inner and the outer diaphragm fixing points are stationary relative to each other, and a drive element connected to a pump drive for deflection of the annular diaphragm is attached between the outer and inner fixing points.
Dosing at small and very small pump capacities with the help of quick-running diaphragm pumps presents the problem that with increasing structural miniaturization, the production, especially of the diaphragm and its attached, preferably molded-on steel parts, is very difficult and/or non-economical. The high rpms of such diaphragm pumps are necessary so that the valves can work exactly and the tolerances for the manufacture of valve parts do not have to be set too tightly. Here, the diameter of the generally circular diaphragm, that is, the change in volume of the working chamber due to the deflection of the diaphragm, determines the pump capacity of the diaphragm pump, with the diaphragm being moved with the help of a steel connecting rod preferably molded-on in the center of the diaphragm. If the diameter of the diaphragm is very small, for example, approximately 5 mm or even smaller, then the steel connecting rod, which under some circumstances has a diameter of less than 1 mm, can be molded-on only with great difficulty. In addition, for such a miniaturization, it is also difficult to manufacture the hydraulic or pneumatic connections to the inlet and outlet valves of the working chamber. Despite the very small dimensions of the diaphragm with a diameter of, for example, 5 mm, a pump capacity of approximately 25 ml per minute would be achieved already for a working rpm of 3000 rotations per minute and a stroke of 0.8 mm. However, in many applications it would be desirable, to realize these or also smaller pump capacities with acceptable yet easily handled pump sizes.